The use of an air-actuated pipeline system for moving wheeled vehicles is generally old as shown in U.S. Pat. Nos. 3,797,405 and 3,881,425. However, any debris in the pipeline will tend to interfere with the movement of the vehicles. Since such systems are well suited for the transportation of particulate solids, there exists the possibility of inadvertent spillage of such solids in the pipeline. One feature of the present invention is the provision of means for removing particles or debris from the pipeline. The wheeled vehicles have a round cross-sectional area similar to but smaller than the interior of the pipeline and may function as pipeline sweepers. That is, the pressure is greater on the rear of the vehicle than on the front and some air flows around the vehicles to blow smaller particles ahead of the vehicle. Those particles which are too large to be blown ahead of the vehicle will collide with the vehicle and will be rolled and slid ahead of the vehicle. The additional energy required to move particles by rolling and sliding by the vehicle plus the possibility of a larger particle wedging the vehicle against the pipe walls are incentives to remove spilled material and debris from the pipeline as quickly as possible.
Furthermore, in order to prevent any vehicle from turning over in the pipeline and spilling its load in the pipeline, it is desirable that the vehicles maintain an upright running attitude. While vehicles having toed out wheels for self-righting a vehicle have been provided in the past, such as disclosed in U.S. Pat. No. 2,928,357, such toed out load wheels are not automatic, but required control lines connected to the vehicle and actuated from outside the line. The present invention provides an automatic self-righting vehicle using toed out wheels but overcomes the objections of the prior art.